When you run smbd -V on your Snow Leopard installation, you'll see it's running SAMBA version 3.0.28a-apple. While I'm not sure how much difference the "-apple" makes, version 3.0.28a is old. Very old. In other words, it's riddled with bugs. Apple hasn't updated SAMBA in 3 years, and for Lion, they're dumping it altogether for something homegrown. The reason? SAMBA is now GPLv3.

No gnome and kde don't have there own SMB clients. They have frontends to samba tech.

I knew KDE (or rather Dolphin) navigated SMB shares using KDE libraries in kdelibs, but after having a dig around it seems you are right and that kdelibs then references samba APIs (and thus kdelibs needs to be compiled with SAMBA dependencies to support SMB).

Most front ends directly call SAMBA where as Dolphin called kdelibs I made the (incorrect) assumption that KDE's SMB support was built inhouse.